Service life and predicted residual fatigue life have always been important topics in rolling bearing research. Lifetime research includes: materials, heat treatment, processing, surface treatment and other technologies; and the prediction of residual fatigue life is generally: predicting the occurrence of fracture by monitoring some precursors of fracture (such as acoustic emission) before bearing fracture.

1. X-ray diffraction

     The X-ray characteristic parameters are mainly: residual stress, martensitic full width at half maximum (HVB) and retained austenite. Bearing fatigue has a high correlation with HVB changes and can be used to analyze bearing residual fatigue life.

     The HVB is dimensionless (reduction ratio), that is, the reduction ratio of the rolling bearing contact surface HVB divided by the value of the internal HVB. Through the analysis of the fatigue level of the fully quenched bearing, even if the bearing load is different or the contact form of the bearing is different, there is still a good correlation between the bearing fatigue and the HVB reduction ratio. However, since the contact surface HVB of the surface hardened bearing has a small reduction ratio and a large fatigue dispersion, it is difficult to evaluate the residual fatigue life.

2. Surface horizontal polar shear wave

     Surface horizontal polar shear wave (surface SH wave), using a simple ultrasonic measurement system to pass through the surface of the sample, by measuring the propagation velocity of the surface SH wave (the progress of rolling fatigue will slow the propagation of surface SH wave Speed) Estimate the fatigue of the bearing for on-site measurement, easy and easy to operate. It makes up for the shortcomings of X-rays that are difficult to use for carburized bearings.

      The effect of measuring the ambient temperature and the surface roughness of the rolling contact portion of the bearing on the surface SH wave propagation time can be eliminated by measuring the distance at different distances.

      A flat probe is used as the SH sensor design to measure any diameter (inner ring raceway). However, the flat type sensor is only suitable for line contact bearings and cannot be applied to surface hardened point contact bearings.

3. LR wave

     Develop sensors that can be applied to the inner ring of deep groove ball bearings. The sensor can meet the following functions:

     1) Ultrasonic waves can converge at the bottom of the inner channel;

     2) LR waves can propagate in the circumferential direction at the bottom of the channel;

     3) LR waves and specular reflected waves can be received separately;

     4) The LR wave can enter the rolling fatigue layer.

Reprinted from the network